With the rapid development of network transmission technologies, more and more contents can be provided over the Internet. For example, users can read news, listen to music, watch movies, and download application programs over the Internet. Web Cache technology is an available solution that is capable of more effectively providing users with contents on a network, reducing load of application servers, and saving transmission (backhaul) bandwidth between radio access network and core network.
FIG. 1 is a schematic diagram of a network cache system. For ease of understanding, the network cache system is simplified, where UMTS represents a Universal Mobile Telecommunications System, and LTE represents a Long Term Evolution system. A cache edge node (the cache edge server 13 in FIG. 1) is deployed on a radio access network (RAN). A cache token server 15 is deployed on a core network. A cache core node (the cache core server 1a in FIG. 1) is deployed on an egress of a gateway GPRS support node (GGSN) 17 or an egress of a PDN gateway (PGW) 19. GPRS stands for general packet radio service, and PDN stands for packet data network.
A basic principle of the network cache system is as follows: A content copy of an application server 2 may be cached in the cache core server 1a and the cache edge server 13. After determining that the content copy has been cached in the cache edge server 13, the cache core server 1a adds a flag to a Transmission Control Protocol (TCP) Option (TCP Option) field and instructs the cache token server 15 to perform a TCP payload replacement. The cache token server 15 replaces a TCP payload that matches the cached content with a token of several bytes. The cache edge server 13 finds, according to token server information, the cached content copy in the cache edge server 13, restores the replaced TCP payload, and sends the replaced TCP payload to user equipment 11.
Although the existing network cache technology can reduce the load of the application server and save the transmission bandwidth between the radio access network and the core network, before sending the restored TCP packet to the user equipment 11, the cache edge server 13 needs to wait until a TCP packet of the cache core server 1a is restored. Therefore, download speed of the user equipment 11 is not further improved. Moreover, the existing network cache technology requires deployment of three types of nodes: the cache core server 1a, the cache token server 15, and the cache edge server 13, and costs are high.